The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Induction heating such as eddy current heating refers to the process of heating an electrically conductive material such as a metal, metal compound, or metal alloy by inducing circulating currents therein from a proximate alternating magnetic field. Hysteretic heating is another form of induction heating that results from alternating the magnetic domains in a strong magnetically susceptible material such as iron, nickel, cobalt, and alloys thereof, as well as compounds containing their oxides also by proximity to an alternating magnetic field. When the magnetic susceptibility of an electrically conductive material is small, heating is primarily generated by eddy currents, and the magnetic flux path is usually not significantly altered by the conductive material. When the magnetic susceptibility of an electrically resistive compound is large, heating is primarily hysteretic, and stray magnetic fields may be reduced by a low reluctance path that can channel a significant portion of the magnetic flux through the magnetic material. For ferromagnetic materials that exhibit both high electrical conductivity and strong magnetic susceptibility, both eddy current and hysteretic heating occur together.
When done properly, a hysteretic heating solution should have less stray magnetic field than a solely eddy-current solution because the magnetic flux flowing through a ferromagnetic material with high magnetic permeability such as iron will tend to travel through the low reluctance path provided by the magnetic material as long as the flux it contains is well within the saturation limits of the material so that it remains highly permeable.
An induction heater generally consists of an electromagnet, through which a high-frequency alternating current (AC) is passed. Induction heaters may be used in numerous applications such as forming, annealing, and welding metals. Induction heating systems have also been employed for heating water to produce steam for humidification purposes. Such humidifying systems, however, generally include many intervening thermal layers that impede the transfer of heat from the heater to the body of water or large masses with relatively small surface area. Consequently, these systems may operate with drawbacks to conventional heaters in that they take longer to heat their intended target or are unable to transfer as much heat to the target, thereby increasing heating costs and reducing the potential efficiency of the solution.